This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This study will compare the pH values at defined time periods immediately post placement when the effect of anesthesia will be the greatest with the pH values obtained from later time periods including the second day after placement. The hypothesis of this study is that propofol anesthesia does alter esophageal pH. pH measurements immediately after capsule placement that are significantly different from the pH measurements at later times will be considered evidence in favor of the hypothesis. Our results may help identify a post-anesthesia period during which pH studies may not be reliable.